Abstract

An analysis of suspended particulate matter (SPM) and phytoplankton distribution, composition and vertical particle fluxes in Russkaya Gavan’ Bay (Northern Island of the Novaya Zemlya), Bezymyannaya Bay (Southern Island of the Novaya Zemlya), Dolgaya Bay (northwestern part of the Vaigach Island) in comparison with the data from the Svalbard Archipelago is presented. Field studies were carried out by the authors during the 9th expedition of the RV “Professor Logachev” in September 1994, the 11th, 13th, and 14th expeditions of the RV “Akademik Sergey Vavilov” in September-October 1997 and August-September 1998. The data about Spitsbergen fjords are from literature. Our results show that, on the bays of the Barents Sea islands, most SPM stays in the bays (fjords) and only small part of it reaches the open sea. This is due to the hydrodynamic conditions in the bays, the large size of the particles, flocculation, and often to the morphological barriers in the relief at the bay entrances. It is important for ecological purposes to map out migration pathways of the SPM with pollutants from bays to the open sea. Results of our investigation indicate that the western bays of the Novaya Zemlya act as traps for SPM derived from glaciers and coastal abrasion.

1. Introduction

The suspended particulate matter (SPM) is an important link in the natural cycle of matter. Its study in the Ocean is necessary for understanding modern sedimentation processes and for the ecological assessment of the state of the environment [1, 2]. Currently, SPM in the Arctic is studied insufficiently in order to receive the complete picture of the sedimentation process in the severe polar conditions [3, 4].

The fjords of the archipelagos and islands are one of sediment sources for the Barents Sea [5]. The intensive glacial meltwater discharge and riverine runoff occur on the Novaya Zemlya and Svalbard archipelagos [6–9]. Studies in fjords receiving glacial meltwater show diversity of biogeochemical and sedimentological processes taking place there [10–14]. SPM in glacier-influenced fjords of western coast of the northern Novaya Zemlya was studied by Medvedev and Potekhina [6] using filtration through the old type filters (nitrocellulose membrane), which increased the values of SPM concentration because of the colmatage [15]. Since 1996 SPM in fjords of the northern Novaya Zemlya was studied by modern methods [16–20]. SPM in fjords of the Svalbard was studied by scientists from different countries [5, 9, 12–14, 21].

Some fjords of the Novaya Zemlya Archipelago are also the damping places of the nuclear waste. It is important for ecological purposes of the region monitoring to map out migration pathways of the SPM with pollutants from bays to the open sea [22].

Particle fluxes have been studied in detail in the western Barents Sea, the Norwegian Sea, the Greenland Sea, and in the Fram Strait [23–30]. The first studies of particle fluxes in the Kara Sea and in the eastern Barents Sea were carried out in September 1993 during the 49-th cruise of the RV “Dmitry Mendeleev” [31] and in August-September 1994 during the 9-th cruise of the RV “Professor Logachev” [32–34].

We have carried out a comparative analysis of SPM and phytoplankton distribution and composition and of the vertical particle fluxes in Russkaya Gavan’ Bay (Northern Island of the Novaya Zemlya), Bezymyannaya Bay (Southern Island of the Novaya Zemlya), Dolgaya Bay (northwestern part of the Vaigach Island), and in the fjords of the Svalbard Archipelago.

2. Materials and Methods

Field studies were carried out during the 9th expedition of the RV “Professor Logachev” in September 1994, the 11th, 13th, and 14th expeditions of the RV “Akademik Sergey Vavilov” in September-October 1997 and August-September 1998 (Figures 1–3; Tables 1 and 2).

Table 1: Coordinates, dates, and concentrations of the SPM in the bays of the Barents Sea.

For SPM studies the filtration of water samples was carried out through Nuclepore membrane filters 47 mm in diameter (pore size 0.45 μm). For vertical particle flux studies, we used small cylindrical sediment traps (vinil plastic cylinders, 118 mm in diameter, with a 490 mm high working part and baffled grid installed in the upper part to avoid washing out of the sediments). Prior to sediment trap deployment, we poured into the flasks 5 mL 40% formalin to eliminate bacterial activity and to prevent the settled particles from being eaten by zooplankton.

For studying the SPM distribution and to establish the correlation between the SPM concentration and the beam attenuation coefficient, we used “Del’fin” transparency probe. Its measurement range is 0.01–8.00 m−1 with absolute accuracy 0.005 m−1 on the 555 nm wave length [3]. Spatial distribution of SPM in the surface waters of the Barents Sea was assessed using the data of the ocean color scanner SeaWiFS (data of the second and third levels were verified by the measurements in situ in time of satellite passing; the algorithm was modified for the Barents Sea) [35].

For plankton studies, we used method of reverse filtration (1–6 L of the water) through the membrane nuclear filter (the pore size was 1 μm), then the sample was concentrated again up to the volume 5–6 mL. The counting and determination of algae and microzooplankton were carried out in the counting camera with volume 0.05 mL by microscope MBI-3 with magnification of 210–420 times.

We used laser-optical counter of the particles CIS-1 (Galai, Israel) in Alfred-Wegener Institute of Polar and Marine Researchers (Bremerhaven, Germany) for granulometric studies of the SPM from the filters in the range 0.5–100 μm. Filters were also studied in the scanning electron microscope JSM-U3 (Jeol, Japan).

In more details the methods of SPM and particle flux studies are described elsewhere [18, 31, 33, 34].

3. Results and Discussion

3.1. Quantitative Distribution of the SPM in the Bays

In the Russkaya Gavan' Bay, it was the period of active melting of the glacier. The SPM concentration in the surface layer in the inner part of the bay was >10 mg/L, reaching value of 265 mg/L near the Shokalsky Glacier edge (Figure 1). In the outer part of the bay, SPM concentration in the surface layer was from 2 to 10 mg/L, and in adjacent Barents Sea it was <2 mg/L [36]. The concentration of SPM decreases under the picnocline.

On September 26-27, 1994 in the inner part of the Bezymyannaya Bay, SPM concentration (Figure 2) was >3 mg/L, decreasing towards the open sea, where concentration is <1 mg/L [18]. We could assume that suspended matter mostly deposits in the outer part of the bay. The SPM concentrations in the area of the river tributary were relatively low, so the influence of the river was insignificant and the abrasion prevailed as the source of the suspended matter during the period of our investigations.

In the Dolgaya Bay of Vaigach Island, the SPM concentration was relatively low (0.15–2.58 mg/L). The decreasing of SPM concentration occurs also from inner part of the bay to the open sea (Figure 3).

The high concentrations of the SPM were observed in the other bays of the Novaya Zemlya Archipelago. For example, in the Inostrantsev Bay, the SPM concentrations were 13.05 mg/L in the surface waters, decreasing under the picnocline and towards the open sea [20].

The SPM concentrations of such degree were observed in the fjords of the Svalbard Archipelago too; in the Kongsfjorden in 1999, the concentrations on the surface were more than 400 mg/L near the glacier edge and 2-3 mg/L in the outer part of the bay [13], in the Hornsund Bay in July 2002 the values were 12.1–19.5 mg/L [37], and in the Grønfjorden in 2001-2002 summers they reached 25.4 mg/L [12]. In the Adventfjorden tidal flat, the SPM concentration in the July 2002 was 911.3 mg/L, and it decreased sharply as the distance from the river mouth increased [9]. The distribution on the surface of the area and on the vertical is similar to the Novaya Zemlya bays.

The investigations have shown a good comparability between the optical measurements and data on natural SPM concentration. The spatial distribution of SPM on the sea surface obtained from the data of the SeaWiFS ocean color scanner agrees with the field in situ data (the correlation coefficient is equal to 0.91) [35]. The regression equation was calculated as
where is SPM concentrations (mg/L), is index of backscattering by the suspended matter (m−1), calculated using the algorithm [35].

For vertical distribution of SPM in the Arctic, the presence of two maximums is typical: in the surface and (not always) in near-bottom (nepheloid) layers [3], but in our investigations in the bay the appreciable increasing was not observed in the bays (Figure 4). We have added the optical scanning of the water column to the sampling on the definite depths, and the regression equation was calculated as
where is SPM concentrations (mg/L), is attenuation coefficient (m−1) [36]. The correlation between SPM concentration and beam attenuation coefficient was 0.94 for more than 100 measurements.

3.2. Composition of the SPM

The granulometric composition of the suspended matter is mainly pelitic. The size of the particles is 1–5 μm (middle pelitic fraction) (Figures 5 and 6, Table 3). In the outer parts of the bays, the size of the particles has grown probably because of the increase of the biogenic component of the suspended matter.

Table 3: Granulometric composition of the particulate matter in the bays of the Novaya Zemlya Archipelago and Vaigach Island (sizes of particles are in μm).

Figure 6: Granulometric composition of the surface SPM on the st. 985 (Russkaya Gavan’ Bay): (a) accumulation curve of the counting concentration of the particles; (b) histogram of the counting concentration of the particles; (c) accumulation curve of the particle’s volume distribution; (d) histogram of the particle’s volume distribution.

The lithogenic particles prevailed in the composition of the suspended matter in the coastal zone and in the bays (Figure 7(a)). In the direction to the open sea, the role of the biogenic component of the suspended matter (phytoplankton—such as diatoms, dinoflagellates) increases (Figure 7(b)) [38, 39]. Surface phytoplankton in the Russkaya Gavan’ Bay was very poor (average numbers concentration was 365 cells/L and biomass −4.2 mg/m3), and it had gone to the autumn stage of development [40]. Dinoflagellates were the most numerical group (46%), and diatoms had only 18%. Only some cells had chromatophores (Chaetoceros decipiens, Pterosperma undulata, Protoperidinium bipes, and P. brevipes). The concentration of diatom cells with chromatophores (“living cells”) was equal to the number of empty valves (65–50 cells/L). Conditions for algae life are bad here because high contents of mineral suspended matter coming from glaciers. Similar situations with the plankton impoverishment of the water in the fjords with glaciers were described in the Spitsbergen fjords [41–43].

3.3. Vertical Particle Fluxes

The location of the mooring stations with the sediment traps is shown on Figure 8. Low values of the particle fluxes (from 5.8 to 17.7 mg m−2 d−1) and particulate organic carbon fluxes (from 0.5 to 1.59 mg C m−2 d−1) from the euphotic zone were measured in the open sea, which is evidence for an ultraoligotrophic character of the studied area [44] during the time of expedition. Much higher particle fluxes were registered in the outer part of Russkaya Gavan’ Bay, Novaya Zemlya Archipelago (up to 7660 mg m−2 d−1), and in the Karskie Vorota Strait (up to 2040 mg m−2 d−1).

Particle flux at the station ASV-5 in the Russkaya Gavan’ Bay (76°16′N, 62°27.1′E, water depth 104 m) at 70 m was 346 mg m−2 d−1, and organic carbon flux was 2.47%. Particle flux at 85 m depth (19 m above the sea bottom) at this station was 7660 mg m−2 d−1. Particulate matter collected by sediment traps in the open sea areas consisted mainly of amorphous aggregates (“marine snow”) and pellets of Crustacea (Figure 9). In the bays sedimentary matter consisted mainly of mineral grains, only few empty diatom valves were found here. Conditions for algae life is bad here because of the high contents of mineral suspended matter coming from the land.

The high values of the vertical particle fluxes were described in fjords of Spitsbergen: Kongsbreene (933000 mg m−2 d−1) near the melting glacier [45], Adventfjorden (over 1000000 mg m−2 d−1) at the front of the river mouth [9], and Greenfjorden −180000 mg m−2 d−1 in 2005–2009 summers [14, 46]. The high rates of the sedimentation were marked in the fjords of the polar archipelagoes [47]. So, the suspended matter of the fjords is mainly deposed in the bay or near the outlet. The investigations in similar fjords of Alaska [48] showed that the sedimentation of the mainly volume of the suspended matter from the glaciers is occurred in the fjord or not far from the bay, only occasionally the undercooled near-bottom waters bring them into the deeper areas.

4. Conclusions

In general, on the archipelagos and islands of the Barents Sea SPM mostly deposits in bays (fjords), and only small part of it is delivered to the open sea because of the hydrodynamic conditions in the bays, the large size of the particles, flocculation, and morphological barriers in the relief on the enter of the bays [49]. It is important for ecological purposes to know the ways of migration of the SPM with pollutants from bays to the open sea. Our investigations allowed us to say that the bays of the Novaya Zemlya Archipelago are the traps for the suspended matter from the glaciers and coast abrasion, and the pollutants from the Novaya Zemlya will stay in the bays.

Acknowledgments

The studies were supported by Russian Fund of Basic Research (Grant 11-05-00087), Russian Ministry for the Education and the Science (Grant NSh-3714.2010.5), and the Earth Sciences Department of Russian Academy of Sciences (Project “Nanoparticles in the Earth’s geospheres”). The practical help of masters and crews of the RV “Professor Logachev” and “Akademik Sergey Vavilov” is acknowledged. The authors are grateful to Academician A. P. Lisitzin, G. I. Ivanov, N. A. Aibulatov, R. Stein, and P. V. Boyarsky for support.

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